“I don’t think we celebrate the Balfour Declaration but I think we have to mark it because I think it was a turning point in the history of that area and I think the most important way of marking it is to recognise Palestine. The British government have said they will do, it's just a question of when the time is right and it seems to me this is the time,” Thornberry said.

'I think we have to mark it because I think it was a turning point in the history of that area and I think the most important way of marking it is to recognise Palestine'

- Emily Thornberry, shadow foreign secretary

Thornberry will be attending an official dinner at which the Israeli Prime Minister Benjamin Netanyahu will be present. She will be going in place of the Labour leader Jeremy Corbyn who was invited but will not attend. Thornberry said she feared that Israel had "lost its way" and was heading for a one-state reality.

“And in that way they are letting down the Israeli people because you cannot have a democratic, Jewish one state in that area. So they will have to choose.”

She acknowledged that Lord Balfour's letter had been a "turning point in the history” of the region, but that today Britain should measure all of its actions and statements on Israel by the standard of whether they will secure two viable states.

Asked whether she felt uneasy that no Palestinian representatives had been invited to the official dinner, Thornberry said she would be attending a Balfour meeting with Palestinians as well.

Action on embassy scandal

The shadow foreign secretary also revealed that the Labour Party would be carrying out a review into the conduct of an Israeli embassy official Shai Masot, now that regulatory body Ofcom has cleared the Al Jazeera investigation which revealed his covert activities in Britain.

Thornberry, a former criminal defence lawyer, said that the rule of law was paramount: “That is a message that I would not be giving out… He is saying that if British people are found in Syria or Iraq and another group captures them, that the British government is saying they should be killed. These people should be brought to court and they should be charged and tried. The rule of law is an important principle and I was surprised to hear him say that.”

BAE Systems 'on notice'

The shadow foreign minister also revealed that Labour would ban arms sales to Saudi Arabia, if it continued using the weapons Britain supplied for its war in Yemen.

She said there was a prima facie case that British arms were being used to kill civilians: "We should not be selling arms until there is a proper international independent investigation into what has happened, looking at both sides, but on the face of it the Saudis are bombing agricultural lands, schools, weddings, funerals.”

The aftermath of an air strike, conducted by the Saudi-led coalition, in Sanaa (AFP)

Thornberry also tore into Defence Secretary Michael Fallon for telling the House of Commons Defence Committee recently that criticism of Saudi Arabia imperilled the sale of a second batch of Typhoon fighter aircraft to Riyadh.

'It's not my job to be supportive of the government. It's my job to hold them to account. And I will hold them to account on this'

“Let me just make this clear. If Fallon does not like me doing this, then tough. Because it's not my job to be supportive of the government. It's my job to hold them to account. And I will hold them to account on this.”

BAE Systems employs 34,000 people in the UK, 9,000 of which are in Warton in Lancashire, where the Eurofighter Typhoon is assembled. Many of those employed are members of Unite, a major trade union backer of Corbyn.

Asked about the consequences of job losses in Lancashire, many of them Unite members, Thornberry said she was putting British arms suppliers “on notice”.

“Now there are a number of countries where we sell arms to and it seems to me that our arms industry has always been lateral thinking and have been very creative. They need to know that if a Labour government is elected and if the Tories have not by that stage stopped selling arms to Saudi to use in Yemen, or the Saudis have not changed their policy, we will stop selling arms to Saudi Arabia. They are on notice.”

Moral anchor

She said British foreign policy has lost its “moral anchor” and a Labour government would restore Britain’s voice in the world with a policy which would put human rights and international law at its core.

“Post-Brexit we are scrabbling around the world trying to find trade deals and we seem to have lost our moral anchor. It does not have to be like that. Of course you have to be pragmatic and I am not saying we are going to be starry eyed, but there needs to be more in your relations with foreign countries than the need for trade deals.”

Doha's Corniche. Thornberry says the current UK government has lost its 'moral anchor' on foreign policy (Reuters)

She said the sovereign wealth funds of the Gulf states were so important to the British economy that Britain had become paralysed out of fear of upsetting economic allies.

“Because we are dependent on everybody in the area. We don’t have anything to say about the cold war between Saudi and Iran. Because we dare not really get into it. So we back off.”

Thornberry said that she and Corbyn would carefully review the Tory government policy of giving immunity from prosecution to Egyptian generals who had command and control responsibility for alleged war crimes in Rabaa Square in 2013. In a carefully phrased answer, Thornberry said that "we have an over-riding duty, which is to prosecute for war crimes".

Trump

Asked about how a future Labour government would handle US President Donald Trump, Thornberry said Britain should not be kowtowing to a president who was “fundamentally unpredictable”.

“I think he is temperamentally unfit for office. I do not think he has the calm and the strength to be leader of the free world,” she said.

She said she did not think that Trump represented the values of the America she recognises and that Britain should be “perfectly clear” about not agreeing with him.

'We should be learning ways of getting around him [Trump]. But we should not be kowtowing to him, holding his hand'

“I think the Foreign Office have been a bit complacent about this. I think they thought that everything would be okay on the Paris climate change agreement. Boris [Johnson, British foreign secretary] even told me in the House that I was being unnecessarily pessimistic about it. And I was not. I was right. And he said I was being unnecessarily pessimistic about the Iran deal and that Trump would come round. Well he has not.”

She said the US constitution appeared to be containing Trump: “We should be learning ways of getting around him. But we should not be kowtowing to him, holding his hand.”

Nor did she spare Johnson, the foreign secretary. She said he did not have the understanding and analysis of foreign affairs that he should have: “It used to be that if you wanted to be the leader of the party you would work at the very best at the job you were doing. Sometimes I think that Boris is looking so hard at how he is going to be the next prime minister, he overlooks the day job.”